Silicon Capacitive Microphone Dual PCB Height Reduction
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Solution Overview
Problem
Existing silicon-based capacitive microphones, such as MEMS microphones, face challenges in reducing their height while maintaining effective signal-to-noise ratio and efficient electrical connectivity between components.
Innovation Solution
The design incorporates a configuration with two printed circuit boards and a connecting member with a supporting body and connecting poles to electrically connect the MEMS transducer to a controlling chip, forming a space between the boards to reduce the microphone's height and enhance signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the microphone uses a conventional single-PCB structure with MEMS transducer and controlling chip mounted on the same board, then the electrical connectivity is simple, but the height cannot be reduced effectively and the signal-to-noise ratio deteriorates
Solution Approach 1:
The invention divides the conventional single-PCB structure into two separate PCBs: a first PCB for mounting the MEMS transducer and a second PCB for mounting the controlling chip. This segmentation allows independent optimization of each board's function and spatial arrangement, enabling reduced microphone height while maintaining proper electrical connectivity through connecting members, thereby improving signal-to-noise ratio by separating analog and digital domains.
Solution Approach 2:
The invention transitions from a planar single-PCB layout to a three-dimensional stacked configuration with two PCBs arranged in different layers. The connecting members (such as rigid flexible PCBs or wire bonds) bridge the two layers, utilizing the vertical dimension to reduce the overall footprint and height while maintaining electrical connectivity, thus resolving the contradiction between compact size and signal quality.
2Length of moving object
If the first PCB and second PCB are positioned close together, then the microphone height is reduced, but electrical connectivity between the MEMS transducer and controlling chip becomes difficult to achieve
Solution Approach 1:
The invention introduces connecting members as intermediary elements between the first PCB and second PCB. These connecting members (such as rigid flexible PCBs, wire bonds, or spring contacts) serve as mediators that enable electrical connectivity across the reduced distance between the two boards, allowing compact height while maintaining reliable signal and power transmission between the MEMS transducer and controlling chip.
Solution Approach 2:
The invention employs rigid flexible PCBs as connecting members, which combine the structural support of rigid PCBs with the flexibility and thin profile of flexible circuits. These thin-film connecting members can bridge the gap between the two PCBs at reduced heights while maintaining electrical conductivity, thus enabling compact design without sacrificing connectivity reliability.
3Ease of manufacture
If the microphone uses a compact single-PCB design, then the manufacturing process is simple, but the back chamber volume is insufficient affecting signal quality
Solution Approach 1:
The invention segments the housing and PCB structure into two separate layers, creating distinct spaces for the MEMS transducer and controlling chip. This segmentation allows the back chamber to be formed in the space between the two PCBs, effectively utilizing the vertical dimension to provide sufficient back chamber volume for acoustic performance while maintaining a compact overall form factor that remains manufacturable using standard assembly processes.
Solution Approach 2:
The invention utilizes the vertical dimension by stacking two PCBs at different heights, creating a three-dimensional space for the back chamber. This dimensional transition from planar to volumetric design allows sufficient back chamber volume to be achieved within a compact footprint, maintaining ease of manufacture through standardized PCB and housing assembly techniques while improving acoustic performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces the microphone's height and improves the signal-to-noise ratio by allowing for efficient electrical connectivity and a larger back chamber, enhancing overall performance.
Implementation Method 1
a moveable diaphragm separated from the backplate for forming a capacitor. While external sound waves reach the diaphragm, the diaphragm will be activated to vibrate relative to the backplate, which changes the distance between the diaphragm and the backplate and changes the capacitance value. As a result, the sound waves are converted into electrical signals.
Data Source
AI summary
A silicon based capacitive microphone includes a first printed circuit board, a second printed circuit board far away from the first printed circuit board, a transducer electrically mounted on the first printed circuit board, a controlling chip electrically mounted on the second printed circuit board, a connecting member located between the first and second printed circuit boards.